When Savchenko was detained, it was alleged she called herself the 'Devil's Duchess", and in one image she was shown holding a recently-killed puppy's heart with the caption: "It's for you Anubis" – the original Egyptian "god of the dead".

She claimed that she needed "to be constantly covered in blood to feel warmth", she said.

Her clothing in macabre online postings is shown smeared in blood from the dead animals.

The pair will also be charged with a separate allegation of armed robbery, while Savchenko and Smyshlyaev, 18, faces court accused of duping a man on a date with an underage girl, and then seeking to blackmail him by accusing him of being a paedophile.